Quote Originally Posted by richard View Post
if your scope probes are ac coupled to measure rail noise [ as they should be ] then the DC offsets visible on the scope are not coming from your circuit the scope provides them , the drift you see is random, for stability each and every scope probe gnd reference lead needs to be connected to the same point


ps warning , do not try to measure rails that don't share a common gnd reference , or exceed the scopes safe working voltage
Ok.


All rails come from the same source; 5VDC.

And they all share the ground to that circuit.